Carburetor idle speed control



Dec. 16, 1969 D. D. SIMPSON EI'AL 3,484,084

CARBURETOR IDLE SPEED CONTROL Filed July '7, 1967 7? g DONALD D. samp ia RAYMOBQJD G. HENNEMANN F i G. 3 7 4 1 WW ATTQRNEY United States Patent 3,484,084 CARBURETOR IDLE SPEED CONTROL Donald 1). Simpson and Raymond G. Hennemann, St. Louis, Mo., assignors to ACF Industries, Incorporated, New York, N .Y., a corporation of New Jersey Filed July 7, 1967, Ser. No. 651,819 Int. Cl. F02m 11/10 US. Cl. 26141 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates a novel arrangement for use in a carburetor embodying an idle fuel system and having a choke valve as well as a throttle valve. One aspect of the device includes a linkage having a rotatable lever with a stepped contact surface, which lever functions as an intermediate member for coordinating the movement and position of the throttle with the choke valve at engine idle speeds. The linkage further includes a collapsible or deformable wall, adjustable element, forming a transitory member, the disposition of the latter being variable to alter the relative position of the throttle with respect to said rotatable lever thereby to achieve and regulate the engine at a preferred idle speed.

In a further aspect of the invention, a deformable wall plastic member is provided in conjunction with a valve body in the engine fuel system to regulate air/fuel flow from the carburetor under engine idle conditions.

BACKGROUND OF THE INVENTION (1) The field of this invention encompasses carburetors and similar charge forming device adapted to cooperate with and regulate the speed of internal combustion engines.

(2) The prior art related to carburetors is extensive, however with respect to control of engine idle speed it is more limited. The art has taught the use of a cooperative relationship between the carburetor throttle and a choke valve, such that an adjustable member may be utilized to translate movement through a linkage connecting the throttle and the choke. The adjustable member is familiar in the art normally as a metallic screw, threaded into an appropriate socket and being rotatably adjustable to set the idle optimum speed position of the throttle as determined by the position of the choke. The adjusting screw, in order to assure its maintaining a predesired stationary setting, is normally provided with locking means such as a lock nut, lock washer, and/or compression spring to avoid rotation of the adjustable member in spite of excessive engine speed and vibrations.

It is understandable that in the course of normal operation of an internal combustion engine, a certain amount of wear will result due to moving contacting parts. Further, the provision of a suitable adjusting screw and its accompanying locking device such as a spring, constitutes a relatively expensive combination which adds to the overall cost of the carburetor.

With respect to metering of idle fuel, it is generally known that a metallic needle valve member in the fuel system offers a satisfactory control expedient.

However with this form of valving, a needle element must be provided with means for maintaining a fluid tight relationship in spite of periodic adjustments. Thus, according to the invention, a deformable wall valve element is provided to rotatably engage a valve body for longitudinally positioning said element to provide a desired fuel flow and also to provide a self sealing valve element.

3,484,084 Patented Dec. 16, 1969 SUMMARY OF THE INVENTION This invention relates in brief to a novel carburetor Construction for regulating an air/fuel mixture, including a linkage for controlling the choke position, and a valve for controlling fuel flow.

The linkage comprises essentially an adjustable coupling including a first member formed of a relatively rigid material and having a constricted opening. A second, elongated member formed of a softer resilient material than the first member includes a smooth surfaced, generally cylindrical shank of a diameter normally slightly greater than the diameter of said constricted opening. Said second member is provided with an axially extending bore underlying said cylindrical surface. A head at one end of the bore may be adapted for urging said shank. into said constricted opening. Thus, the resilient surface of said shank will be inwardly deformed thereby to frictionally position said first member with respect to said second member and to subsequently permit axial adjustment of said shank with respect to said constricted opening by the application of a torsional force to said second member.

A contact tip on one end of the adjusting member shank is adapted to engage a stepped cam surface on a rotatable lever which is in turn operably connected to the carburetor choke. Thus the throttle idle position will be determined by the limitation in movement imposed by the resilient stop.

The disclosed adjusting member provides a positive throttle positioning means which avoids loosening in spite of the degree of engine vibration under running conditions. Further, the adjustable member is found to be a satisfactory replacement for a plurality of parts heretofore utilized to achieve the positioning function. Thus economically the herein described combination provides a more eflicient, and less expensive carburetor, as well as one embodying a readily adjustable feature.

A deformable wall fuel metering valve element positioned in the carburetor includes basically a hollow member defining a thin outer wall. A portion of the member is smooth surfaced, and of a suitable diameter to be tightly received in a threaded opening. The fit between the formed threads and the valve element is adequate to assure a fluid and gas tight annular seal in spite of rotatable adjustment of said element within the valve body.

It is therefore a primary object of the hereinafter disclosed invention to provide an efiicient yet inexpensive adjustable element for use in a carburetor construction.

It is a further object of the invention to provide a deformable wall valve element adapted to be self-sealing Within a valve body solely by virtue of the deformability of said element.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a side elevation view of a carburetor of the type in which the presently disclosed adjusting member is incorporated.

FIG. 2 is a segmentary view on an enlarged scale of a portion of the carburetor shown in FIG. 1, directed particularly to the lever connected to the carburetor throttle, which lever receives the idle adjust device and,

FIG. 3 is a side view of the idle adjust Pin shown removed from its receiving aperture and in a undeflected condition.

FIG. 4 represent a side view in cross section of an alternate embodiment of the adjustable member.

FIG. 5 is an end view of the device shown in FIG. 4.

FIG. 6 is a side view of the member shown in FIGS. 4 and 5.

FIG. 7 is a side elevation in cross section taken along the longitudinal axis of a deformable wall valve element of the type contemplated.

FIG. 8 is a side elevation of the valve element shown removed from its threaded receptacle and FIG. 9 is an embodiment of the disclosed insertable member including a locking element.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The novel adjusting pin or device, together with the valve element, are adapted for use on a number of carburetor types particularly those which utilize a choke as well as a throttle valve connected through an appropriate linkage. In that virtually all carburetors usually incorporate a fuel idle system, it is understandable that the arrangement of an idle adjusting valve and a linkage connecting the throttle and the choke will vary in accordance with the carburetor basic construction.

FIG. 1 of the drawings illustrates a typical carburetor of the type contemplated which includes an elongated body 10 comprising an inlet 11 for receiving an air filter, not presently shown. A discharge outlet 12 is adapted to connect to the intake manifold of an internal combustion engine. Body portion 10, communicating inlet 11 and discharge outlet 12 comprises in general a mixture conduit 13 wherein incoming air is mixed with a predetermined amount of metered liquid fuel to form a combustible air/fuel mixture which is passed to the engine inlet manifold.

Following normal construction, the carburetor is provided with a choke valve 14 as well as a throttle valve 16. Choke valve 14 is mounted at the upper portion of mixture conduit 13 adjacent inlet 11, and is carried on a choke valve shaft 17 which protrudes from an external wall of the body. Shaft 17 is provided with an offset actuating lever 18 at the protruding end. The lower portion of the carburetor body is provided in the normal manner with throttle valve 16 connected to, or mounted to a throttle shaft 19 which, in a similar manner protrudes from a wall of the body, carrying a throttle control lever 21. Said control lever 21 is connected in turn to a push rod 22 directly engageable with a control mechanism which might be either manually or pedally operated as in the instance of an automotive engine, to regulate engine speed.

An intermediate lever 23 is pivotally carried on a pin 24 depending from an external wall of body 10 intermediate the air inlet 11 and discharge 12. Lever 23 includes a radially extending arm 26 having means for receiving a connecting rod 27 which is connected to lever 18 to coordinate movement of said lever 23 with the position of choke valve 14.

While not presently shown, choke valve 14 may be controlled by, and is usually connected to a thermally responsive element such as a thermo coil or the like. This member functions to adjust the position of choke valve 14 in accordance with the. temperature of the engine to facilitate both easy starting of the engine and economical operation after operating temperature has been achieved.

Intermediate lever 23 includes a peripheral contacting or cam surface having a plurality of progressively depressed steps 29, 31 and 32 which permit the carburetor to idle at diiferent speeds depending on en ine temperature. Thus, after starting, as the engine achieves a satisfactory running temperature, the position of intermediate lever 23 will be rotated in response to expansion of the thermally responsive element. The latter has in turn positioned choke 14 normally in the wide open position to provide a minimum of choking action.

To coordinate the idle position of throttle 16 with the position of the choke valve 14, control lever 21 is provided with an upstanding tab 33 disposed generally normal to the lever surface. Said lever is further provided with a constricted opening or receiving aperture 34. Idle adjusting pin 36 is received within constricted aperture 34 and includes a contact tip 37 disposed adjacent to one of the engaging steps 29, 31 or 32. Thus, with the engine operating under idle conditions, contacting tip 37 of the pin 36 will engage one of the stepped surfaces, thereby to properly position the throttle valve.

DESCRIPTION OF THE IDLE ADJUST PIN Referring to FIGS. 2 and 3, idle adjust pin 36 includes an elongated shank 38 preferably of cylindrical construction having contact tip 37 at one extremity. The other extremity is provided with a head 39 extending coaxial of shank 38, which head may be irregularly shaped on the outer surface to permit gripping for rotating the pin into receiving opening 34. A transverse slot 41 formed in the head is adapted to accommodate the blade of a screwdriver or other suitable tool.

An elongated bore 42 extending axially of shank 38 forms a thin Wall 43 of substantially uniform thickness. Bore 42 as seen in FIG. 2, extends from the end face of the head 39 and terminates adjacent contact tip 37. Although the cavity defined by bore 42 presently disclosed is open at but one end, it may in the alternative be open at the tip end also to facilitate manufacture of the pin. For the present application, a closed tip is to be preferred since this portion of the pin is subjected to constant wear by repeated contact with lever 23.

In accordance with the invention, adjusting pin 36 is formed preferably or at least partially, of a thermoplastic resinous material having the physical characteristic of being temperature stable, resilient, and resistant to the deleterious affect of aromatic fuels. For example it is found that materials such as nylon, and Deln'n exhibit the necessary resistant qualities and still permit forming of a rigid yet yieldable thin wall.

In the instance of either of the above mentioned materials, wall 43 is so formed to be resiliently inwardly yieldable as the pin shank 38 is either rotated or urged into a constricted opening. The degree of constriction is of course contingent on the outside diameter of shank 38. However, to achieve the necessary radial outward force, the shank may assume a non-circular cross section to permit the Wall to be inwardly deformed at peripherally spaced apart points. It is essential in either instance that upon insertion of the tip and shank into a constricted opening, a sufficient torque or axial force will be required such that the pin wall will yieldably deform thereby establishing a frictional resistance to both further progress, or withdrawal of the pin.

In the instance of a rotatably insertable pin, opening 34 is provided with a smooth surfaced, preferably noncutting thread as shown in FIG. 2 having root and crown diameters; thus, as the pin is rotatably driven into opening 43 it will be advanced to a desired position. As the shank emerges from the far side of the opening, the thin wall tends to resume its normal disposition so long as the wall material has not exceeded the limit of elastic deformation.

While not shown, the constricted aperture comparable to aperture 34 in FIG. 2, may be smooth walled thus permitting the pin to be forced directly into the opening by application of a longitudinal force. Such arrangement however must be non-rotatable and a greater reliance will thus be placed on the frictional force established between the contact surfaces of the mating elements rather than upon the reactive force formed by the smooth faced above mentioned thread.

Referring to FIGS. 2 and 3 illustrating a preferred usage of the adjusting pin, the latter is rotatably urged into opening 34 to contact the stepped edge of the lever 23. Thus with carburetor choke 14 set to a fully closed position, and with throttle 16 positioned to give a desired engine speed, adjusting pin 36 is rotated until tip 37 engages the lower most step 29 of lever 23 thus establishing the throttle position for the particular choke position.

Following normal carburetor operation, as choke 14 is adjusted to open in response to raising engine temperature, lever 23 is rotated to align the tip 37 with the low idle steps 31 and 32 thereby allowing throttle 16 to further close and limit the engine idle speed.

The outside diameter of shank 38 is preferably not so oversized as to be permanently marred or damaged while being urged through the constricted locking aperture 34. The provision of sharp cutting edges on the aperture, although assuring a firm grip, would tend to gouge out a groove in the soft shank surface as the pin is rotated and is therefore not recommended. Such a groove however is not entirely undesirable, it is understandable though that it would reduce effective holding ability when the pin is rotated to a withdrawn position.

FIGS. 4 and 5 illustrate an alternate embodiment of the novel adjusting pin characterized in that the elongated surface of shank 47 is provided with a plurality of upstanding flutes 46 which extend the length of the shank. With respect to locking this embodiment of the adjusting pin in place, the peripherally spaced flutes 46 slideably engage a corresponding constricted opening. As the flutes bear inwardly against the thin wall defined by shank 46 and bore 48, the thin wall will deflect inwardly thus establishing a reactive frictional force to resist further free movement of the pin within the constricted opening.

DESCRIPTION OF THE NEEDLE VALVE ELEMENT FIGS. 7 and 8 illustrate a preferred embodiment of the invention in which the adjustable needle valve member 60 is carried in a threaded opening in the carburetor wall in such a position as to regulate fuel flow through passage 62 connected with the carburetor mixture conduit. The valve element comprises basically an elongated body 64 having a head 66 at one end provided with a transverse slot 68 to accommodate an adjusting tool.

The body other end is provided with a shank 70 having a conical tip 72 disposed in registry with seat 73 in passage 62. Shank 70 may be formed of a suitable metal and fastened into the body 64. However, depending on design requirements, shank 70 may also be molded into and become an integral part of the shank.

Cavity 79 extends axially through the body, opening at head 60 to define a thin resilient wall. As shown in FIGS. 7 and 8, an enlarged portion 76 is provided to form an engaging surface with the threads in threaded opening 74.

In the instance of a valve member 60 rotatably received in opening 74, a dual effect will be achieved. First, the outer surface of enlarged portion 76 will provide an annular seal against leakage of air through passage 74 thus providing uniformity. Secondly, said member 60 will be rotated to properly position tip 72 within passage 62 thereby defining an annular opening at seat 73 of a sufficient cross section to insure the proper amount of fuel to the engine under idle conditions.

As seen particularly in FIG. 7, with the valve member in position, the wall of said member 60 will be collapsed inwardly thereby exerting a restraining force against free movement of the valve member which would otherwise alter the valve setting in seat 73.

It is contemplated that the present valve element and cooperating parts may be formed with a suflicient degree of accuracy to minimize the need to adjust the valve. Thus, annular shoulder 75 at the underside of head 66 will be brought into tight engagement with the body wall thereby to form a seal. Under such circumstances, tip 72 and its mating seat 73 are so designed to form a sufficiently large opening to pass the necessary amount of fuel under engine idle conditions.

In the instance of an application wherein it is desirable to fixedly position the adjustable element such as a tamper-proof device, means may be provided in conjunction with the resilient walled element to lock the same. As shown in FIG. 9, the carburetor idle adjust valve is similar to that shown in FIGS. 7 and 8 with the additional element of an expanding pin 81 which is frictionally held within cavity 79. Said pin may be of a non-yielding material such as metal. However, it may also be formed of a resilient plastic material. In either instance the pin is adapted to fully enter the shank axial bore. Further insertion of the pin into the bore will provide a tight fit of the pin in the constricted portion of the bore, thus locking the adjustable member into place.

We claim:

1. An adjustable coupling device comprising:

(a) a first member formed of a relatively rigid material and having a threaded constricted opening.

(b) a second elongated member of relatively softer, resilient and elastic material than said first member,

(0) said second member including a shank portion providing a smooth outer generally cylindrical surface having a diameter greater than the diameter of said constricted opening, said shank portion having an axially extending bore underlying said generally cylindrical surface,

(d) and a head portion adapted to receive a tool for urging said second member into the constricted opening, in said first member whereby:

when said shank portion of said second member is forced into said constricted opening of said first member, said cylindrical surface of said shank portion is elastically and resiliently deformed and conformed to the shape of the said constricted opening Without cutting said surface, by displacement of the material underlying said generally cylindrical surface into said bore;

whereby, said second member may be infinitely adjusted axially relative to said opening by application of torsional force to said head portion and said second member will be held in an axially adjusted position relative to said constricted opening by the inherent elasticity and resiliency of the material of said second member and including a locking member carried in said second elongated member and including a pin having a locking portion characterized by a diameter less than the diameter of said axially extending bore, and greater than the cross-sectional area of the opening formed by said bore when the outer surface of said shank is deformed inwardly toward said bore whereby the locking portion of said pin will be tightly received in the constricted portion of said bore.

2. In an adjustable coupling as defined in claim 1 wherein said adjusting pin is formed of a substantially unyielding material.

3. In an adjustable coupling as defined in claim 1 wherein said adjusting pin is formed of a relatively yieldable elastic material.

4. In a carburetor including a body defining a mixture conduit communicating with a supply of air for forming an air/fuel combustible mixture;

(a) a valve means in said body to regulate the fuel flow to the mixture conduit and including,

(b) a threaded valve passage connected to a supply of fuel and having a port opening into said mixture conduit,

(c) a valve operator rotatably received in said threaded passage and including,

(1) a metering portion disposed in registry with said port to form an annular fuel channel,

(2) an elongated resilient shank having an enlarged portion adapted to engage the threads in said valve passage and to form an annular seal therewith,

(3) a bore extending axially of said shank to define a relatively thin wall,

(4) said shank enlarged portion being radially inwardly deflected into said bore thereby to frictionally position said valve operator with respect to said valve passage and to form an annular liquid tight seal.

5. In a carburetor as defined in claim 4 wherein said valve metering portion depends axially from one end of said resilient shank, and a head depends from the other end thereof for rotatably adjusting said operator in said threaded passage.

6. In a carburetor as defined in claim 4 wherein said threaded passage in said carburetor is defined by a substantially smooth walled portion to avoid cutting of said shank portion when the latter is rotatably inserted into said threaded passage.

7. In a carburetor as defined in claim 4 including a locking pin adapted for insertion into said bore, a portion thereof having a diameter greater than the diameter of the cross-sectional area of the opening formed by the said wall in said bore whereby said locking pin when disposed in said constricted bore inwardly of said constricted wall, the latter will be wedged into position.

References Cited UNITED STATES PATENTS Marsh 156- 7 Patzschke et al. 151-7 X Kahn.

Olson et a1.

Rapata 151-7 Parks 151-7 X McSeveny 26152 Jones 1517 Kalert.

Brown 1517 X Donovan.

US. Cl. X.R. 

